CN112816399A - Standard sample for circulating salt spray corrosion test of vehicle steel plate and preparation method thereof - Google Patents
Standard sample for circulating salt spray corrosion test of vehicle steel plate and preparation method thereof Download PDFInfo
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- CN112816399A CN112816399A CN202011617570.7A CN202011617570A CN112816399A CN 112816399 A CN112816399 A CN 112816399A CN 202011617570 A CN202011617570 A CN 202011617570A CN 112816399 A CN112816399 A CN 112816399A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
- G01N17/006—Investigating resistance of materials to the weather, to corrosion, or to light of metals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
Abstract
A standard sample for a circulating salt spray corrosion test of a vehicle steel plate and a preparation method thereof belong to the field of quality control in the aspect of a salt spray corrosion test of an automobile. The preparation method of the standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle comprises the steps of raw material screening, sample plate cutting, sample plate processing, processing of an area to be detected, electrophoretic paint spraying and the like. The standard sample prepared by the invention is suitable for the confirmation of a detection method, the confirmation of a non-standard method, the evaluation of a new method and the quality assurance of the whole detection process of the circulating salt spray corrosion test of the vehicle steel plate; reagent acceptance and quality control, personnel assessment, relevant detection laboratory capability evaluation, laboratory-to-laboratory comparison and the like; the uniformity and the stability of the sample meet the requirements of a standard sample, the good uniformity and the stability of the sample can be ensured, the preparation method of the sample is scientific, the uniformity and the stability are good, the success rate is high, and the use is convenient.
Description
Technical Field
The invention belongs to the field of quality control in the aspect of automobile salt spray corrosion tests, and particularly relates to a standard sample for a circulating salt spray corrosion test of an automobile steel plate and a preparation method thereof.
Background
With the development of the automobile industry and the popularization of automobiles, the metal corrosion problem of whole automobiles, parts and materials is increasingly concerned, and various quality problems and complaints fed back by consumers in the using process are more and more. On the other hand, China is a vast country, and the actual conditions of climate conditions, temperature and humidity, rain and snow fall, snow removal and the like in different regions are greatly different.
The salt spray test is an environmental test for examining the corrosion resistance of products or metal materials by mainly utilizing the artificial simulated salt spray environmental conditions created by salt spray test equipment, and comprises neutral salt spray and acidic salt spray, wherein the corrosion factors comprise temperature, humidity, sodium chloride solution concentration, pH value and the like. The copper ion accelerated acid salt spray test is a rapid salt spray corrosion test, and a small amount of copper salt-copper chloride is added into a salt solution to strongly induce corrosion. The circulating corrosion test is improved and upgraded on the basis of the traditional salt spray test box, and can be used for simultaneously performing salt spray, humidity (high temperature and high humidity, low temperature and low humidity), air drying (hot drying and air drying) and other environmental condition tests. At present, the whole automobile factories, part suppliers, material suppliers and inspection and detection organizations in China have great differences in the aspects of evaluation standards and evaluation methods adopted in corrosion tests. Therefore, it is necessary to standardize and improve the detection and evaluation capability of the domestic laboratory in the aspect of automobile salt spray corrosion so as to promote the quality improvement and standardization of the industry. At present, the standard sample in the field still belongs to the blank field. The salt spray test standard sample with good uniformity and stability is prepared, randomness and uncertainty in the detection process can be avoided, and the capability of a detection laboratory is truly reflected. The method has special significance for improving the quality control level of a laboratory, ensuring the quality of related products, even breaking the international trade barrier and improving the competitiveness of related products in China.
Disclosure of Invention
The invention aims to provide a standard sample for a circulating salt spray corrosion test of a vehicle steel plate, and aims to solve the problem of difference between detection results caused by different detection personnel, equipment, reagents, environmental conditions and the like. The invention also aims to provide a preparation method of the sample, which ensures that the sample has good uniformity and stability, high success rate and convenient use.
The technical scheme adopted by the invention for realizing the purpose is as follows: the standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle is characterized in that: the standard sample is a low-carbon steel plate for the vehicle, which is manufactured by a certain preparation method, is provided with a spray paint coating which is the same as that of a sample automobile, and is provided with a region to be detected with a fixed size, and the region to be detected is stuck with an adhesive tape made of a specific material.
The standard sample is cut into a raw material sample plate according to the size of 101.56mm multiplied by 76.14mm multiplied by 0.86mm by means of laser cutting.
The surface of the steel plate of the standard sample except the area to be measured is provided with a paint spraying coating layer which is the same as that of the sample automobile.
The position, 47mm away from the upper edge, of the front surface of the standard sample steel plate is an area to be detected, the size of the area is 66mm multiplied by 17mm, a high-temperature-resistant adhesive tape without silicon-based components is attached to the area, and the steel plate at the position where the adhesive tape is attached is free of paint spraying coatings.
The temperature resistance range of the high temperature resistant adhesive tape is-54-320 ℃.
The preparation method of the standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle is characterized by comprising the following steps of: the preparation process comprises three steps of raw material screening, sample preparation and sample uniformity and stability inspection.
In the raw material screening, Q345 low-carbon steel used for manufacturing automobiles is selected as a sample raw material, the carbon content is 0.02-0.08%, and the stability is excellent; the adhesive tape stuck on the area to be detected is a high-temperature resistant adhesive tape without silicon-based components.
The sample preparation comprises the following steps: template cutting-template clearance-template preliminary treatment-electrophoresis spray paint-stoving-sample is beaten sign indicating number, and packing-storage specifically includes following flow:
cutting a template: performing laser cutting by using a high-speed optical fiber laser cutting machine, and cutting the selected steel plate according to the size in claim 2; punching a unique serial number at the bottom of each steel plate to identify each sample wafer, removing a cutting fast opening through a grinding wheel chamfering machine, and forming a fillet;
secondly, cleaning a sample plate: sequentially carrying out oil removal, cleaning, derusting and polishing on the cut sample plate for later use;
thirdly, preprocessing a sample plate: clamping the processed sample plate on a spray painting clamp, and sequentially performing oil removal, cleaning and low-zinc phosphate or oxygen broccoli treatment;
fourthly, electrophoretic painting: hanging the preprocessed sample plate on an electrophoresis fixture by adopting a polyurethane electrophoresis paint process, entering an electrophoresis tank at a constant speed, and performing electrophoresis paint spraying;
baking: after the template finishes electrophoretic paint spraying, the template enters a baking device to bake the paint;
sixthly, printing a code on the sample, and packaging: marking the prepared sample steel plate, and filling the sample steel plate into a packaging bag with a proper size to finish sample preparation; the packaging bag adopts two layers of packaging, wherein the first layer is an internal waterproof oil wax paper and an external PE sealing bag, so that the samples are prevented from being rubbed in the transportation process or damaged by a humid environment, the second layer is a uniformly customized hard cowhide packaging box, and a plastic foam buffer is added in a paper box;
and storage: the packaged samples were stored at room temperature.
The homogeneity and stability tests of the samples were carried out according to GB/T15000.3-2008 "Standard sample working guide (3) general principles and statistical methods for Standard sample valuing".
The raw materials of the invention are low-carbon steel plates used for manufacturing automobiles, the stability is good, and the material quality is consistent with that of an actual sample; the electrophoretic paint spraying mode adopted for preparing the sample has good uniformity and good protection effect, and can fully ensure the uniformity and stability of the standard sample; the sample prepared by the invention is suitable for the confirmation of related detection methods, the confirmation of non-standard methods, the evaluation of new methods and the quality assurance of the whole detection process; reagent acceptance and quality control, personnel assessment, relevant laboratory capacity evaluation, and equal laboratory-to-laboratory ratio. The preparation method of the sample is scientific, has good uniformity and stability, high success rate and convenient use.
Drawings
FIG. 1 is a process flow diagram of the present invention.
FIG. 2 is a diagram of a standard sample according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following drawings and specific embodiments, but the present invention is not limited to the specific embodiments.
Example 1
As shown in figure 2, the standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle is made of Q345 low-carbon steel used for manufacturing the vehicle, and the carbon content of the steel plate is 0.02-0.08%, the standard sample is the low-carbon steel plate for the vehicle made by a certain preparation method, and is provided with a paint spraying coating which is the same as that of a sample vehicle, a region to be detected with a fixed size is arranged on the steel plate, and an adhesive tape made of a specific material is attached to the region to be detected.
The standard sample is cut into a raw material sample plate according to the size of 101.56mm multiplied by 76.14mm multiplied by 0.86mm by means of laser cutting.
The surface of the steel plate of the standard sample except the area to be measured is provided with a paint spraying coating layer which is the same as that of the sample automobile.
The position, 47mm away from the upper edge, of the front surface of the standard sample steel plate is an area to be detected, the size of the area is 66mm multiplied by 17mm, a high-temperature-resistant adhesive tape without silicon-based components is attached to the area, and the steel plate at the position where the adhesive tape is attached is free of paint spraying coatings.
The temperature resistance range of the high temperature resistant adhesive tape is-54-320 ℃.
Example 2
The standard sample preparation protocol described in example 1 includes three steps of raw material screening, sample preparation, sample homogeneity and stability testing.
Firstly, screening raw materials
In the raw material screening, Q345 low-carbon steel used for manufacturing automobiles is selected as a sample raw material, the carbon content is 0.02-0.08%, and the stability is excellent; the adhesive tape stuck on the area to be detected is a high-temperature resistant adhesive tape without silicon-based components.
Second, sample preparation
The sample preparation comprises the following steps: template cutting-template clearance-template preliminary treatment-electrophoresis spray paint-stoving-sample is beaten sign indicating number, and packing-storage specifically includes following flow:
cutting a template: performing laser cutting by using a high-speed optical fiber laser cutting machine, and cutting the selected steel plate according to the size in claim 2; punching a unique serial number at the bottom of each steel plate to identify each sample wafer, removing a cutting fast opening through a grinding wheel chamfering machine, and forming a fillet;
secondly, cleaning a sample plate: sequentially carrying out oil removal, cleaning, derusting and polishing on the cut sample plate for later use;
thirdly, preprocessing a sample plate: clamping the processed sample plate on a spray painting clamp, and sequentially performing oil removal, cleaning and low-zinc phosphate or oxygen broccoli treatment;
fourthly, electrophoretic painting: hanging the preprocessed sample plate on an electrophoresis fixture by adopting a polyurethane electrophoresis paint process, entering an electrophoresis tank at a constant speed, and performing electrophoresis paint spraying;
baking: after the template finishes electrophoretic paint spraying, the template enters a baking device to bake the paint;
sixthly, printing a code on the sample, and packaging: marking the prepared sample steel plate, and filling the sample steel plate into a packaging bag with a proper size to finish sample preparation; the packaging bag adopts two layers of packaging, wherein the first layer is an internal waterproof oil wax paper and an external PE sealing bag, so that the samples are prevented from being rubbed in the transportation process or damaged by a humid environment, the second layer is a uniformly customized hard cowhide packaging box, and a plastic foam buffer is added in a paper box;
and storage: the packaged samples were stored at room temperature.
The homogeneity and stability tests of the samples were carried out according to GB/T15000.3-2008 "Standard sample working guide (3) general principles and statistical methods for Standard sample valuing".
Thirdly, testing the uniformity and stability of the sample
1. Sample homogeneity test
Randomly selecting 20 samples from the samples, and selecting one group of 10 samples according to the requirements of sample testing in a reference instruction book, and referring to GB/T2423.18-2012 environmental test part 2: test methods test Kb: salt spray, alternating (sodium chloride solution), was tested in repeated conditions, i.e. in the same laboratory by the same personnel using the same test methods and instruments in a shorter time.
The judgment principle is as follows: adopting single factor analysis of variance to examine the uniformity of the sample, when F < F0.05If so, judging that the sample is uniform; otherwise, the requirement is not met.
Analysis of variance formula
The uniformity test result shows that the uniformity of the sample can meet the requirement of the capability verification sample. The results of the uniformity test are shown in tables 1 and 2.
TABLE 1 first set of sample homogeneity test results
All results were within ± 2S of the mean, indicating that the heterogeneity of the samples was acceptable.
TABLE 2 second set of sample homogeneity test results
All results were within ± 2S of the mean, indicating that the heterogeneity of the samples was acceptable.
2. And (3) testing the stability of the sample:
randomly selecting 32 samples from the samples, each of which is 16 pieces, placing the samples for 30 days under the room temperature condition (23 ℃ +/-2 ℃ and RH 50% +/-5%), and according to the requirements of sample testing in the reference instruction book, referring to GB/T2423.18-2012 part 2 of environmental test: test methods test Kb: salt spray, alternating (sodium chloride solution), test sample corrosion width on the corrosion test area.
The judgment principle is as follows: performing a series of tests, and performing t test<Significance level a (typically 0.05) degree of freedom is a critical value t of n-1α(n-1)If no significant difference is found between the mean and the reference, the sample is considered to be stable, otherwise the sample is not satisfactory.
Analysis of variance formula
The stability test results show that the samples are stable during the test period, and the requirements of capability verification samples are met. The stability test results of the samples are shown in tables 3 and 4.
TABLE 3 stability test results for the first set of samples
TABLE 4 stability test results for the second set of samples
Claims (9)
1. The standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle is characterized in that: the standard sample is a low-carbon steel plate for the vehicle, which is manufactured by a certain preparation method, is provided with a spray paint coating which is the same as that of a sample automobile, and is provided with a region to be detected with a fixed size, and the region to be detected is stuck with an adhesive tape made of a specific material.
2. The standard sample for the cyclic salt spray corrosion test of the steel plate for the vehicle as claimed in claim 1, wherein: the standard sample is cut into a raw material sample plate according to the size of 101.56mm multiplied by 76.14mm multiplied by 0.86mm by means of laser cutting.
3. The standard sample for the cyclic salt spray corrosion test of the vehicular steel sheet according to claim 1, wherein: the surface of the steel plate of the standard sample except the area to be measured is provided with a paint spraying coating layer which is the same as that of the sample automobile.
4. The standard sample for the cyclic salt spray corrosion test of the vehicular steel sheet according to claim 1, wherein: the position, 47mm away from the upper edge, of the front surface of the standard sample steel plate is an area to be detected, the size of the area is 66mm multiplied by 17mm, a high-temperature-resistant adhesive tape without silicon-based components is attached to the area, and the steel plate at the position where the adhesive tape is attached is free of paint spraying coatings.
5. The standard sample for the cyclic salt spray corrosion test of the vehicular steel sheet according to claim 4, wherein: the temperature resistant range of the high temperature resistant adhesive tape is-54 ℃ to 320 ℃.
6. The method for preparing the standard sample for the circulating salt spray corrosion test of the steel plate for the vehicle as claimed in claim 1, wherein the method comprises the following steps: the preparation process comprises three steps of raw material screening, sample preparation and sample uniformity and stability inspection.
7. The method for preparing the standard sample for the circulating salt spray test of the steel plate for the vehicle as claimed in claim 6, wherein the method comprises the following steps: in the raw material screening, Q345 low-carbon steel used for manufacturing automobiles is selected as a sample raw material, the carbon content is 0.02-0.08%, and the stability is excellent; the adhesive tape stuck on the area to be detected is a high-temperature resistant adhesive tape without silicon-based components.
8. The method for preparing the standard sample for the circulating salt spray test of the steel plate for the vehicle as claimed in claim 6, wherein the method comprises the following steps: the sample preparation comprises the following steps: template cutting-template clearance-template preliminary treatment-electrophoresis spray paint-stoving-sample is beaten sign indicating number, and packing-storage specifically includes following flow:
and storage: the packaged samples were stored at room temperature.
9. The method for preparing the standard sample for the cyclic salt spray corrosion test of the steel plate for the vehicle as claimed in claim 6, wherein the method comprises the following steps: the homogeneity and stability tests of the samples were carried out according to GB/T15000.3-2008 "Standard sample working guide (3) general principles and statistical methods for Standard sample valuing".
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4188824A (en) * | 1978-06-02 | 1980-02-19 | Youngstown Sheet And Tube Company | Coating adherence prospensity testing of metal substrates |
| CN1211289A (en) * | 1996-02-19 | 1999-03-17 | 汉克尔股份两合公司 | Zinc phosphatizing with low quantity of copper and manganese |
| JP2000074804A (en) * | 1998-08-27 | 2000-03-14 | Nkk Corp | Evaluation method for outermost layer of steel plate by transmission electron microscope |
| CN201222019Y (en) * | 2008-07-17 | 2009-04-15 | 武汉钢铁(集团)公司 | Apparatus for sealing sample steel plate edge |
| CN206192848U (en) * | 2016-11-04 | 2017-05-24 | 国网山东省电力公司电力科学研究院 | Salt fog sample packaging hardware |
| CN106814026A (en) * | 2015-12-02 | 2017-06-09 | 鞍钢股份有限公司 | A kind of clad plate corrosion resisting property method for rapidly testing |
| CN107144524A (en) * | 2017-05-22 | 2017-09-08 | 吉利汽车研究院（宁波）有限公司 | Body test cabin accelerated corrosion test method |
| CN109883941A (en) * | 2019-03-22 | 2019-06-14 | 重庆赛飞斯金属材料有限公司 | The method of corrosion stability is tested after a kind of processing of metal material surface |
| CN211627112U (en) * | 2019-11-01 | 2020-10-02 | 唐山钢铁集团有限责任公司 | A banding device for salt atmosphere test sample |
-
2020
- 2020-12-30 CN CN202011617570.7A patent/CN112816399B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4188824A (en) * | 1978-06-02 | 1980-02-19 | Youngstown Sheet And Tube Company | Coating adherence prospensity testing of metal substrates |
| CN1211289A (en) * | 1996-02-19 | 1999-03-17 | 汉克尔股份两合公司 | Zinc phosphatizing with low quantity of copper and manganese |
| JP2000074804A (en) * | 1998-08-27 | 2000-03-14 | Nkk Corp | Evaluation method for outermost layer of steel plate by transmission electron microscope |
| CN201222019Y (en) * | 2008-07-17 | 2009-04-15 | 武汉钢铁(集团)公司 | Apparatus for sealing sample steel plate edge |
| CN106814026A (en) * | 2015-12-02 | 2017-06-09 | 鞍钢股份有限公司 | A kind of clad plate corrosion resisting property method for rapidly testing |
| CN206192848U (en) * | 2016-11-04 | 2017-05-24 | 国网山东省电力公司电力科学研究院 | Salt fog sample packaging hardware |
| CN107144524A (en) * | 2017-05-22 | 2017-09-08 | 吉利汽车研究院（宁波）有限公司 | Body test cabin accelerated corrosion test method |
| CN109883941A (en) * | 2019-03-22 | 2019-06-14 | 重庆赛飞斯金属材料有限公司 | The method of corrosion stability is tested after a kind of processing of metal material surface |
| CN211627112U (en) * | 2019-11-01 | 2020-10-02 | 唐山钢铁集团有限责任公司 | A banding device for salt atmosphere test sample |
Non-Patent Citations (3)
| Title |
|---|
| 国家标准总局: "《测定耐湿热、耐盐雾、耐侯性(人工加速)的漆膜制备法》", 15 September 1979, pages: 1 - 2 * |
| 宋伟伟: "喷漆车身涂层质量稳定性测试研究", 《设计研究》 * |
| 宋伟伟: "喷漆车身涂层质量稳定性测试研究", 《设计研究》, no. 9, 15 May 2020 (2020-05-15), pages 161 - 165 * |
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